Helicobacter pylori (H. pylori) has been implicated in a variety of gastrointestinal diseases such as gastritis, gastric and duodenal ulcers, and gastric malignancies. H. pylori infections are generally persistent, causing chronic gastrointestinal disease. Treating an H. pylori infection can dramatically improve the gastrointestinal health of the patient. Ulcers, for example, become much less likely to recur following successful treatment of an infection. Unfortunately, conventional treatments for H. pylori infections are not always successful. Accordingly, there is a need for assays to confirm that the infection has been cured.
Assays for H. pylori infections have been developed. Many assays are invasive, requiring endoscopy followed by culture, histology, or other procedures. More recently, less invasive methods have been developed. One method tests serum for antibodies to H. pylori (see, e.g., Li et al., Dig. Dis. Sciences, 41: 2142-2149 (1996)); another tests for CO2 produced by H. pylori urease activity (see, e.g., Westblom, Immunol. Invest., 26:163-174 (1997)). Immunoassay and PCR methods to detect H. pylori have also been developed. See, e.g., Gramley et al., J. Clin. Microbiol., 37:2236-2240 (1999); Ishihara et al., Aliment. Pharmacol. Ther., 14: 611-614 (2000); Namavar et al., Eur. J. Clin. Microbiol. Infect. Dis., 14:234-237 (1995); Parsonnet et al., JAMA, 282: 2240-2245 (1999). PCR-based methods may have advantages to some of the other methods (low cost, high throughput, etc.). Unfortunately, PCR-based methods known in the art may lack the specificity to distinguish, for example, a successfully treated patient from a patient with a continuing H. pylori infection. See, e.g., Makristathis et al., J. Clin. Microbiol., 36: 2772-2774 (1998). There exists a continuing need for non-invasive assays to test for and to monitor H. pylori infection and course of treatment.